The present invention relates to an apparatus for processing a surface of a flexible substrate by subjecting the surface of a substrate to successive surface reactions of at least a first precursor and a second precursor, and particularly to an apparatus according to the preamble of claim 1.
In the prior art several types of apparatuses, apparatuses and nozzle heads are used for subjecting a surface of a substrate to successive surface reactions of at least a first precursor and a second precursor according to the principles of atomic layer deposition method (ALD). In ALD applications, typically two gaseous precursors are introduced into the ALD reactor in separate stages. The gaseous precursors effectively react with the substrate surface, resulting in deposition of a single atomic layer. The precursor stages are typically followed or separated by a purge stage that eliminates the excess precursor from the surface of the substrate prior to the separate introduction of the other precursor. Therefore an ALD process requires alternating in sequence the flux of precursors to the surface of the substrate. This repeated sequence of alternating surface reactions and purge stages between is a typical ALD deposition cycle.
The prior art ALD-apparatuses usually comprise a nozzle head having one or more first precursor zones for subjecting the surface of the substrate to the first precursor, one or more second precursor zones for subjecting the surface of the substrate to the second precursor, and one or more purge gas zones or purge gas zones arranged between the first and second precursor zones for subjecting the surface of the substrate to a purge gas. The zones are arranged alternatively in succession to the nozzle head: first precursor zone, purge gas zone, second precursor zone, purge gas zone, first precursor zone, purge gas zone, second precursor zone, and so on. Therefore when the nozzle head is moved on the substrate surface it will produce growth layers according to the principles of ALD method. The nozzle head may also comprise discharge channels arranged between the first and second precursor zone or between a first precursor zone and a purge gas zone or between a second precursor zone and a purge gas zone. The discharge channel is arranged to exhaust precursor and purge gas after the surface of the substrate is subjected to it. Alternatively each of these prior art precursor zones and purge gas zones comprise at least one inlet port for supplying the precursor or purge gas and at least one outlet port for exhausting the precursor or purge gas. Thus there is provided suction to each of the zones for exhausting the precursor or purge gas after the substrate is subjected to it.
As only one atomic layer is produced on the surface of the substrate during one ALD-cycle, the nozzle head is formed to comprise several first and second zones such that a single scan with the nozzle head over the surface of the substrate forms several atomic layers on the surface of the substrate. The single scan with the nozzle head may be done by moving either the nozzle head or the substrate. In the prior art the number of scan with the nozzle head is increasing by moving the nozzle head with a linear movement back and forth by a moving mechanism using fast speed for performing multiple scans over the surface of the substrate.
This prior art way for producing several atomic layer has the disadvantage that the back and forth movement with the moving mechanism produces great mechanical forces the nozzle head has to stand. The forces are especially high as the nozzle head has be stopped in the end position and accelerated again. Therefore the apparatus and the nozzle head are susceptible to damages as the acceleration and deceleration are carried by a motor. Furthermore, the oscillating back and forth movement between the end positions requires accelerating the nozzle head over and over again which consumes a lot of energy.